The objective of this research is to elucidate the molecular basis of the catabolism of VLDL-derived lipoproteins. Well defined structural alterations in VLDL will be introduced by specific chemical and enzymatic modifications. We intended to modify either separately or in combination, all three components of VLDL. Lipids will be removed by organic solvent or enzymatic hydrolysis. Protein will be digested by nonspecific proteolytic enzymes. Carbohydrate moieties of lipoproteins will be hydrolyzed by endoglycosidase and exoglycosidase. After the characterization of structural changes introduced by these treatments, the resulting VLDL derivatives will be compared with the native particles as regards their binding activities. Both liver membrane and fibroblast will be tested as possible target tissues for each of VLDL derivatives prepared. The unique structural features in each VLDL derivatives will then be correlated with their binding activity. From this experiment, we hope to identify the specific structural features which determine the catabolism of VLDL.